Process tube



FIG. 1 is a perspective view of a process tube;

FIG. 2 is a side plan view of the process tube;

FIG. 3 is an end plan view of the process tube;

FIG. 4 is a top plan view of the process tube;

FIG. 5 is a bottom plan view of the process tube; and,

FIG. 6 is a cross-sectional view of the process tube taken along line 6in FIG. 4.

CLAIM The ornamental design for a process tube, substantially as shownand described herein.